1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 1996, Nickolay Dudorov 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice unmodified, this list of conditions, and the following 12 * disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 */ 30 31 /* 32 * 'nos-tun' program configure tunN interface as a point-to-point 33 * connection with two "pseudo"-addresses between this host and 34 * 'target'. 35 * 36 * It uses Ip-over-Ip incapsulation ( protocol number 94 - IPIP) 37 * (known as NOS-incapsulation in CISCO-routers' terminology). 38 * 39 * 'nos-tun' can works with itself and CISCO-routers. 40 * (It may also work with Linux 'nos-tun's, but 41 * I have no Linux system here to test with). 42 * 43 * BUGS (or features ?): 44 * - you must specify ONE of the target host's addresses 45 * ( nos-tun sends and accepts packets only to/from this 46 * address ) 47 * - there can be only ONE tunnel between two hosts, 48 * more precisely - between given host and (one of) 49 * target hosts' address(es) 50 * (and why do you want more ?) 51 */ 52 53 /* 54 * Mar. 23 1999 by Isao SEKI <iseki@gongon.com> 55 * I added a new flag for ip protocol number. 56 * We are using 4 as protocol number in ampr.org. 57 * 58 */ 59 60 #ifndef lint 61 static const char rcsid[] = 62 "$FreeBSD$"; 63 #endif /* not lint */ 64 65 #include <sys/types.h> 66 #include <sys/ioctl.h> 67 #include <sys/signal.h> 68 #include <sys/socket.h> 69 70 #include <net/if.h> 71 #include <netinet/in.h> 72 #include <netinet/in_systm.h> 73 #include <netinet/ip.h> 74 75 #include <arpa/inet.h> 76 #include <fcntl.h> 77 #include <netdb.h> 78 #include <stdio.h> 79 #include <stdlib.h> 80 #include <string.h> 81 #include <syslog.h> 82 #include <unistd.h> 83 84 /* Tunnel interface configuration stuff */ 85 static struct ifaliasreq ifra; 86 static struct ifreq ifrq; 87 88 /* Global descriptors */ 89 int net; /* socket descriptor */ 90 int tun; /* tunnel descriptor */ 91 92 static void usage(void) __dead2; 93 94 static int 95 Set_address(char *addr, struct sockaddr_in *sin) 96 { 97 struct hostent *hp; 98 99 bzero((char *)sin, sizeof(struct sockaddr)); 100 sin->sin_family = AF_INET; 101 if((sin->sin_addr.s_addr = inet_addr(addr)) == INADDR_NONE) { 102 hp = gethostbyname(addr); 103 if (!hp) { 104 syslog(LOG_ERR,"unknown host %s", addr); 105 return 1; 106 } 107 sin->sin_family = hp->h_addrtype; 108 bcopy(hp->h_addr, (caddr_t)&sin->sin_addr, hp->h_length); 109 } 110 return 0; 111 } 112 113 static int 114 tun_open(char *dev_name, struct sockaddr *ouraddr, char *theiraddr) 115 { 116 int s; 117 struct sockaddr_in *sin; 118 119 /* Open tun device */ 120 tun = open(dev_name, O_RDWR); 121 if (tun < 0) { 122 syslog(LOG_ERR,"can't open %s - %m", dev_name); 123 return(1); 124 } 125 126 /* 127 * At first, name the interface. 128 */ 129 bzero((char *)&ifra, sizeof(ifra)); 130 bzero((char *)&ifrq, sizeof(ifrq)); 131 132 strncpy(ifrq.ifr_name, dev_name+5, IFNAMSIZ); 133 strncpy(ifra.ifra_name, dev_name+5, IFNAMSIZ); 134 135 s = socket(AF_INET, SOCK_DGRAM, 0); 136 if (s < 0) { 137 syslog(LOG_ERR,"can't open socket - %m"); 138 goto tunc_return; 139 } 140 141 /* 142 * Delete (previous) addresses for interface 143 * 144 * !!!! 145 * On FreeBSD this ioctl returns error 146 * when tunN have no addresses, so - log and ignore it. 147 * 148 */ 149 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) { 150 syslog(LOG_ERR,"SIOCDIFADDR - %m"); 151 } 152 153 /* 154 * Set interface address 155 */ 156 sin = (struct sockaddr_in *)&(ifra.ifra_addr); 157 bcopy(ouraddr, sin, sizeof(struct sockaddr_in)); 158 sin->sin_len = sizeof(*sin); 159 160 /* 161 * Set destination address 162 */ 163 sin = (struct sockaddr_in *)&(ifra.ifra_broadaddr); 164 if(Set_address(theiraddr,sin)) { 165 syslog(LOG_ERR,"bad destination address: %s",theiraddr); 166 goto stunc_return; 167 } 168 sin->sin_len = sizeof(*sin); 169 170 if (ioctl(s, SIOCAIFADDR, &ifra) < 0) { 171 syslog(LOG_ERR,"can't set interface address - %m"); 172 goto stunc_return; 173 } 174 175 /* 176 * Now, bring up the interface. 177 */ 178 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) { 179 syslog(LOG_ERR,"can't get interface flags - %m"); 180 goto stunc_return; 181 } 182 183 ifrq.ifr_flags |= IFF_UP; 184 if (!(ioctl(s, SIOCSIFFLAGS, &ifrq) < 0)) { 185 close(s); 186 return(0); 187 } 188 syslog(LOG_ERR,"can't set interface UP - %m"); 189 stunc_return: 190 close(s); 191 tunc_return: 192 close(tun); 193 return(1); 194 } 195 196 static void 197 Finish(int signum) 198 { 199 int s; 200 201 syslog(LOG_INFO,"exiting"); 202 203 close(net); 204 205 s = socket(AF_INET, SOCK_DGRAM, 0); 206 if (s < 0) { 207 syslog(LOG_ERR,"can't open socket - %m"); 208 goto closing_tun; 209 } 210 211 /* 212 * Shut down interface. 213 */ 214 if (ioctl(s, SIOCGIFFLAGS, &ifrq) < 0) { 215 syslog(LOG_ERR,"can't get interface flags - %m"); 216 goto closing_fds; 217 } 218 219 ifrq.ifr_flags &= ~(IFF_UP|IFF_RUNNING); 220 if (ioctl(s, SIOCSIFFLAGS, &ifrq) < 0) { 221 syslog(LOG_ERR,"can't set interface DOWN - %m"); 222 goto closing_fds; 223 } 224 225 /* 226 * Delete addresses for interface 227 */ 228 bzero(&ifra.ifra_addr, sizeof(ifra.ifra_addr)); 229 bzero(&ifra.ifra_broadaddr, sizeof(ifra.ifra_addr)); 230 bzero(&ifra.ifra_mask, sizeof(ifra.ifra_addr)); 231 if (ioctl(s, SIOCDIFADDR, &ifra) < 0) { 232 syslog(LOG_ERR,"can't delete interface's addresses - %m"); 233 } 234 closing_fds: 235 close(s); 236 closing_tun: 237 close(tun); 238 closelog(); 239 exit(signum); 240 } 241 242 int main (int argc, char **argv) 243 { 244 int c, len, ipoff; 245 246 char *dev_name = NULL; 247 char *point_to = NULL; 248 char *to_point = NULL; 249 char *target; 250 char *source = NULL; 251 char *protocol = NULL; 252 int protnum; 253 254 struct sockaddr t_laddr; /* Source address of tunnel */ 255 struct sockaddr whereto; /* Destination of tunnel */ 256 struct sockaddr wherefrom; /* Source of tunnel */ 257 struct sockaddr_in *to; 258 259 char buf[0x2000]; /* Packets buffer */ 260 struct ip *ip = (struct ip *)buf; 261 262 fd_set rfds; /* File descriptors for select() */ 263 int nfds; /* Return from select() */ 264 int lastfd; /* highest fd we care about */ 265 266 267 while ((c = getopt(argc, argv, "d:s:t:p:")) != -1) { 268 switch (c) { 269 case 'd': 270 to_point = optarg; 271 break; 272 case 's': 273 point_to = optarg; 274 break; 275 case 't': 276 dev_name = optarg; 277 break; 278 case 'p': 279 protocol = optarg; 280 break; 281 } 282 } 283 argc -= optind; 284 argv += optind; 285 286 if ((argc != 1 && argc != 2) || (dev_name == NULL) || 287 (point_to == NULL) || (to_point == NULL)) { 288 usage(); 289 } 290 291 if(protocol == NULL) 292 protnum = 94; 293 else 294 protnum = atoi(protocol); 295 296 if (argc == 1) { 297 target = *argv; 298 } else { 299 source = *argv++; target = *argv; 300 } 301 302 /* Establish logging through 'syslog' */ 303 openlog("nos-tun", LOG_PID, LOG_DAEMON); 304 305 if(Set_address(point_to, (struct sockaddr_in *)&t_laddr)) { 306 closelog(); 307 exit(2); 308 } 309 310 if(tun_open(dev_name, &t_laddr, to_point)) { 311 closelog(); 312 exit(3); 313 } 314 315 to = (struct sockaddr_in *)&whereto; 316 if(Set_address(target, to)) 317 Finish(4); 318 319 if ((net = socket(AF_INET, SOCK_RAW, protnum)) < 0) { 320 syslog(LOG_ERR,"can't open socket - %m"); 321 Finish(5); 322 } 323 324 if (source) { 325 if (Set_address(source, (struct sockaddr_in *)&wherefrom)) 326 Finish(9); 327 if (bind(net, &wherefrom, sizeof(wherefrom)) < 0) { 328 syslog(LOG_ERR, "can't bind source address - %m"); 329 Finish(10); 330 } 331 } 332 333 if (connect(net,&whereto,sizeof(struct sockaddr_in)) < 0 ) { 334 syslog(LOG_ERR,"can't connect to target - %m"); 335 close(net); 336 Finish(6); 337 } 338 339 /* Demonize it */ 340 daemon(0,0); 341 342 /* Install signal handlers */ 343 (void)signal(SIGHUP,Finish); 344 (void)signal(SIGINT,Finish); 345 (void)signal(SIGTERM,Finish); 346 347 if (tun > net) 348 lastfd = tun; 349 else 350 lastfd = net; 351 352 for (;;) { 353 /* Set file descriptors for select() */ 354 FD_ZERO(&rfds); 355 FD_SET(tun,&rfds); FD_SET(net,&rfds); 356 357 nfds = select(lastfd+1,&rfds,NULL,NULL,NULL); 358 if(nfds < 0) { 359 syslog(LOG_ERR,"interrupted select"); 360 close(net); 361 Finish(7); 362 } 363 if(nfds == 0) { /* Impossible ? */ 364 syslog(LOG_ERR,"timeout in select"); 365 close(net); 366 Finish(8); 367 } 368 369 370 if(FD_ISSET(net,&rfds)) { 371 /* Read from socket ... */ 372 len = read(net, buf, sizeof(buf)); 373 /* Check if this is "our" packet */ 374 if((ip->ip_src).s_addr == (to->sin_addr).s_addr) { 375 /* ... skip encapsulation headers ... */ 376 ipoff = (ip->ip_hl << 2); 377 /* ... and write to tun-device */ 378 write(tun,buf+ipoff,len-ipoff); 379 } 380 } 381 382 if(FD_ISSET(tun,&rfds)) { 383 /* Read from tun ... */ 384 len = read(tun, buf, sizeof(buf)); 385 /* ... and send to network */ 386 if(send(net, buf, len,0) <= 0) { 387 syslog(LOG_ERR,"can't send - %m"); 388 } 389 } 390 } 391 } 392 393 static void 394 usage(void) 395 { 396 fprintf(stderr, 397 "usage: nos-tun -t tunnel -s source -d destination -p protocol_number [source] target\n"); 398 exit(1); 399 } 400 401